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Iron Tin Reaction Kinetics

Dark red iron[III] solution is rapidly reduced to colorless iron[II] by addition of tin[II] chloride solution, with the rate depending on concentration and temperature.

Four medium footed cylinders are prepared with 100 ml of ferric chloride solution 0.01M with potassium thiocyanate solution added to make the dark red complex. One of the solutions should be hot, so just the iron and thiocyanate solutions in that cylinder, with a 150ml beaker for the demonstrator to fill with hot water from the water cooler, right before the demonstration.

The cylinders are on the bench top in...

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Reaction of Magnesium and Air

A magnesium ribbon is held with tongs and lit with a match or torch, making a bright flame that consumes the ribbon from the bottom up.

The ribbon should be about 20-30 cm long. Hold the ribbon with the tongs high and at arms length. Let the magnesium ribbon hang at a steep angle but not vertical. Light the bottom of the ribbon by bringing the end of the torch flame up to ribbon.  Magnesium will melt before it lights, so carefully with the torch. The ribbon can also be lit with a wooden match.

Wear safety glasses and don't look directly at the flame.

Hydrogen Peroxide Decomposition by Iodide

Hydrogen peroxide 30% in a large round flask decomposes to boiling water and oxygen when postassium iodide is added.

The 12L Round Bottom Flask is set on white C-Fold towels covering a large cork ring on the lab bench.  100-150 ml of 30% hydrogen peroxide is carefully poured in. The liquid should be visible against the white towels from the perspective of the class, and any camera, if used.

The catalyst is 5 g of potassium iodide in a small plastic weighing boat labeled KI.

Safety goggles and gloves. Raise the projection screen and make sure the flask is...

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Specific Heat of Air and Water

Two clean plastic cups, one filled with room temperature water, the other empty, for a student to test with their finger.

Supported by experience, this is a way to introduce heat capacity as an important variable in measuring temperature.

Make sure the water has been in the room long enough to equilibrate. Cover the water as any evaporation will cool it.

Food safe cups and potable water. And safety glasses, because why not?

Limiting Reagent, Vinegar or Baking Soda?

Vinegar and two different amounts of baking soda in plastic soda bottles with balloons.

Two 500ml PETN soda bottles of the same make, split a bottle of vinegar between them.

11" balloons are pre-inflated with dry air, with care taken not to stretch the neck of the balloon. Into the balloons with a funnel go one, two teaspoons of baking soday. With 250 ml of vinegar, that's like six liters of gas potential if one carbon dioxide comes from one acid hydrogen ion.

Tap the baking soda powder down away from the neck of the balloon. Stretch the neck and place it over the top...

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Metals in Acid

Curls of zinc and magnesium are dropped into 2M hydrochloric acid, and bubbles observer'd.

A 600ml beaker, clean and clear, is at the focal point of a camera projecting the image of 500 ml of 2M hydrochloric acid.

A curl of magnesium bubbles wildly, skittering across the surface of the acid.

A curl of zinc sinks to the bottom, and bubbles form at a steady rate.

Precipitation of Lead Iodide

Potassium iodide solution is added to lead nitrate solution, and bright yellow lead iodide precipitates.

Potassium iodide solution is 0.1 M and lead nitrate solution is 0.01M.

The lead nitrate solution is about 350 ml in a 600ml beaker, and the KI sol'n is 200 ml in a 400ml beaker. Pour the potassium iodide sol'n into the lead nitrate.

Glasses and gloves. The finished demonstration is stirred and the precipitate and solution goes in the hazardous waste bucket.

Conductivity of Solutions

A light bulb is lit when the conductivity probe is immersed in an ionic solution.

The solutions are all in labeled 250ml beakers. All are about 150 ml of 0.1M sol'n. In order, the solutions are: tap water, distilled water, sodium chloride, sucrose, acetic acid, hydrochloric acid, sodium hydroxide, ethanol, and barium sulfate. (See video: http://youtu.be/4WillWjxRWw?hd=1)

The simple conductivity tester is on the bench, for the instructor to plug in. An 800ml beaker with 400 ml of distilled water is provided as...

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Weighing Moles

Several samples are weighed on the balance; each is a mole.

The electronic scales are set up in front of the video camera. In a secondary container on the scale platform is a cube of lead weighing 208 g., 18 g of water in a bottle with an empty bottle for tare, and 200.6 g of mercury in a bottle with an empty bottle for tare.

Precipitation of Silver Chloride

Sodium chloride solution is added to silver nitrate solution and a white precipitate of silver chloride is instantly formed.

The silver nitrate solution is around 0.1M, and the sodium chloride solution around 0.5M. Pour the sodium chloride sol'n into the silver nitrate to avoid leaving traces of silver nitrate in the empty beaker.

Wear safety glasses and gloves to prepare and perform this demonstration.

Earth's Magnetic Field

OHP representation of lines of force using bar magnet and iron filings.

What it shows:

The magnetic field lines of the Earth can be represented by the field lines of a bar magnet.

How it works:

The Earth's magnetic field is basically a magnetic dipole. It can therefore be represented to first approximation by the field of a bar magnet. The shape of the field lines can be highlighted by the sprinkling of iron filings, or by the use of plotting compasses. The latter method has the advantage of showing the variation of dip...

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Rock Samples

Selection of igneous, sedimentary and metamorphic rocks.

What it shows:

A selection of rocks and minerals available for lecture demonstrations

How it works:

The following samples are available for show-and-tell in lecture. The samples vary in size, and only those marked with a 4 are big enough to be seen.

1. A selection of elements in their natural (unrefined) states:
native copper Cu 4
diamond C iso
gold Au
realgar (silver ore) 4
graphite C hex 4
Silver...

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Astrobrella

Umbrella decorated with the constellations.

What it shows:

The aberration of starlight is the shift in the position of the image of a star due to the rotation of the Earth about the Sun, and is a consequence of the finite velocity of light. For a star directly overhead, a telescope will have to be angled by v/c to the vertical where v = velocity of the Earth in space, in order that the telescope be pointing at the star. The equipment necessary to show aberration is one umbrella.

How it works:

The best way to picture this...

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Spiral Galaxy

Hand held Plexiglass model of spiral galaxy.

What it shows:

Handy size model of a generic spiral galaxy to show salient features or to describe structure of the Milky Way

How it works:

The model is a 30cm diameter Plexiglass disc 1cm in thickness, with a Ping-pong ball stuck through the center to represent the nucleus. The spiral arms of the galaxy are sprayed on with white paint, and we've stuck on a "you are here" arrow pointing to the outer reaches of one of the spiral arms at the approximate position of the Sun in the...

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